1. Field of the Invention
The present invention is related to an equalizer and a method of equalizing signals, and particularly to an equalizer and a method of equalizing signals that adjust a direct current setting and an alternating current setting of the equalizer according to a plurality of direct current terms and a plurality of alternating current terms generated by an oversampling logic unit.
2. Description of the Prior Art
Please refer to FIG. 1. FIG. 1 is a diagram illustrating an equalizer 100 according to the prior art. The equalizer 100 includes a direct current estimator 102, a direct current logic processor 104, an alternating current estimator 106, and an alternating current logic processor 108. After the equalizer 100 receives data from a channel, the direct current estimator 102 averages data received from the channel within a first predetermined time T1 to generate a direct current parameter, and the alternating current estimator 106 executes a discrete cosine transform and a discrete sine transform on the data received from the channel within the first predetermined time T1 to generate an alternating current parameter. The direct current logic processor 104 coupled to the direct current estimator 102 determines how to adjust a direct current setting of the equalizer 100 according to a plurality of direct current parameters within a second predetermined time T2. The alternating current logic processor 108 coupled to the alternating current estimator 106 determines how to adjust an alternating current setting of the equalizer 100 according to a plurality of alternating current parameters within the second predetermined time T2.
In the prior art, although operational principles of the equalizer 100 are based on a locked clock data recovery phase situation, in fact, the equalizer 100 receives data from the channel even when the clock data recovery phase is not locked. In addition, the direct current estimator 102 and the alternating current estimator 106 operate at a frequency of the received data. For example, the frequency of the received data is 10 GHz, and the direct current estimator 102 and the alternating current estimator 106 also operate at 10 GHz. If the data received by the equalizer are all alternating current values during a period of time, the direct current estimator 102 may determine a direct current value of the data is insufficient, resulting in increasing the direct current setting of the equalizer 100. In fact, the data received by the equalizer may all be alternating current values during the period of time, but may not be in another period of time. Thus, the direct current setting of the equalizer 100 may be incorrect.